U.S. patent number 5,326,592 [Application Number 07/699,069] was granted by the patent office on 1994-07-05 for on die solution coating of extruded profiles and apparatus therefor.
This patent grant is currently assigned to GenCorp Inc.. Invention is credited to James R. Goewey, Keith E. Wilson.
United States Patent |
5,326,592 |
Goewey , et al. |
July 5, 1994 |
On die solution coating of extruded profiles and apparatus
therefor
Abstract
A coating apparatus and process for coating selected surface
areas of extruded substrates with decorative or functional coatings
by passing the extruded substrates emerging from the extrusion die
through a coating block. The coating block contains a coating
cavity die conforming to the selected surfaces to be coated wherein
liquid coating is supplied to the coating cavity die in a manner to
selectively coat the selected surfaces on the extruded
substrate.
Inventors: |
Goewey; James R. (Marion,
IN), Wilson; Keith E. (Wabash, IN) |
Assignee: |
GenCorp Inc. (Fairlawn,
OH)
|
Family
ID: |
24807795 |
Appl.
No.: |
07/699,069 |
Filed: |
May 13, 1991 |
Current U.S.
Class: |
427/256; 427/358;
425/461; 264/177.1; 118/404; 118/411 |
Current CPC
Class: |
B29C
48/12 (20190201); B60J 10/17 (20160201); B29C
48/155 (20190201); B05C 3/20 (20130101); B05C
3/12 (20130101) |
Current International
Class: |
B05C
3/12 (20060101); B05C 3/00 (20060101); B29C
47/02 (20060101); B60J 10/00 (20060101); B05C
3/02 (20060101); B05C 3/20 (20060101); B05D
005/00 (); B05C 003/20 () |
Field of
Search: |
;427/256,286,356,357,358
;118/410,411,412,404,405 ;264/171,177.1,177.16,177.17,177.18
;425/131.1,132,133.5,462,461 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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710069 |
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Sep 1941 |
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DE2 |
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2200109 |
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Apr 1974 |
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FR |
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2572678 |
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May 1986 |
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FR |
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60-92821 |
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May 1985 |
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JP |
|
Primary Examiner: Owens; Terry J.
Claims
What is claimed is:
1. An apparatus for applying a coating solution to an extruded
substrate, comprising:
a coating block abuttingly secured to an extrusion die, said
coating block containing at least one coating die cavity opening
which conforms to one or more selected surfaces of a polymeric
substrate emerging from said extrusion die and at least one coating
solution opening, said coating block containing coating means for
supplying a liquid solution polymer coating to said coating die
cavity opening and to one or more of said selected surfaces of said
substrate which surfaces are adjacent to said coating die cavity
opening to coat said one or more selected surfaces, said coating
means including at least one channel communicating with said
coating cavity opening and said coating solution opening, said
coating means being located on the back of the coating block
adjacent the extrusion die whereby the surface of said extrusion
die forms a wall of each said channel, said coating block
cooperating with and being adapted to receive extruded substrate
from said extrusion die.
2. A coating apparatus according to claim 1, wherein said coating
die cavity essentially conforms to the upper surface profile of
said extrudate.
3. A coating apparatus according to claim 1, wherein said extrusion
die has an upper profile configuration and said coating die cavity
conforms to said extrusion die upper profile configuration.
4. A coating apparatus according to claim 2, wherein each channel
terminates in a narrow slit opening, and wherein the narrow
dimension of each slit is adapted to determine the thickness of the
liquid coating applied to said extruded substrate surface.
5. A coating apparatus according to claim 4, wherein said coating
means comprises at least two channels.
6. A coating apparatus according to claim 4, wherein each said slit
opening has a different breadth and is adapted to deposit a surface
coating on said extruded substrate.
7. A coating apparatus according to claim 4, wherein the width of
each said slit opening is different to enable each slit opening to
apply a different thickness of applied coating to said extruded
substrate.
8. A coating apparatus according to claim 1, wherein said coating
means is adapted to apply a continuous surface coating on said
extrudate substrate.
9. A coating apparatus according to claim 1, wherein said coating
means is adapted to be intermittently interrupted to apply a
non-continuous linear surface coating on said extruded
substrate.
10. A coating apparatus according to claim 5, wherein one of said
channels is adapted to deposit continuous linear surface coating
and another of the channels is adapted to deposit a discontinuous
linear surface coating, each said channel opening having a lateral
breadth approximating the intended lateral profile of the applied
surface coating to said extruded substrate.
11. A coating apparatus according to claim 10, wherein said coating
means is operative to coat in conjunction with said coating die
cavity a selected surface of the extruded substrate by applying a
measured amount of liquid coating to said extruded substrate.
12. A process for selectively applying a liquid coating to one or
more selected surfaces on an extrudate, comprising the steps
of:
forming a polymeric extrudate;
selectively coating the one or more selected surfaces of said
extrudate as it emerges from an extrusion die by passing said
extrudate through a coating block abuttingly secured to the
extrusion die, said coating block having at least one coating die
cavity opening which conforms to one or more selected surfaces of
said polymeric extrudate emerging from said extrusion die and at
least one coating solution opening, said coating block containing
coating means including at least one channel communicating with
said coating cavity opening and said coating solution opening, said
coating means being located on the back of the coating block
adjacent the extrusion die whereby the surface of said extrusion
die forms a wall of each said channel, and
supplying said coating die cavity with a liquid solution polymer
coating which is applied to said one or more selected surfaces of
said extrudate.
13. The process of claim 12, wherein said coating solution is
applied continuously on selected surfaces of said extrudate.
14. The process of claim 12, wherein said coating solution is
applied intermittently on selected surfaces of said extrudate.
15. The process of claim 12, wherein one of said channels applies a
continuous coating to selected surfaces on the extruded substrate
and the other said channel applies a coating intermittently on
other selected surfaces of said extrudate.
16. The process of claim 12, wherein said coating means applies
different thickness of coating to selected surfaces of said
extrudate by having narrower or larger discharge openings provided
in said channels.
17. An apparatus for solution-coating an extrudate, comprising:
a coating block for applying at least one liquid solution polymer
coating to a polymeric extrudate;
said coating block being adapted to be abuttingly secured to an
extrusion die and having a coating die cavity opening which
conforms to a selected surface of said polymeric extrudate emerging
from said extrusion die and having a coating solution opening, said
coating block containing coating means including a channel
communicating with said coating cavity opening and said coating
solution opening, said coating means being located on the back of
the coating block adjacent the extrusion die whereby the surface of
said extrusion die forms a wall of said channel, said coating block
cooperating with and being adapted to receive said extrudate
directly from an extrusion die.
18. A solution coating process, comprising the steps of;
extruding a polymeric article through a die plate, providing a
coating block abuttingly secured to the die plate and in alignment
with said extruded article, said coating block having at least one
coating die cavity opening which conforms to one or more selected
surfaces of said extruded article emerging from said die plate and
having at least one coating solution opening, said coating block
containing coating means including at least one channel
communicating with said coating cavity opening and said coating
solution opening, said coating means being located on the back of
the coating block adjacent said die plate whereby the surface of
said die plate forms a wall of each said channel, said coating
block cooperating with and being adapted to receive said extruded
article from said die plate,
feeding at least one liquid polymer coating solution to said
coating block having said at least one channel therein
communicating with a preselected surface of said extruded article
to be coated, and
applying said at least one liquid polymer coating solution to said
preselected surface of said extruded article as it emerges from
said die plate.
Description
FIELD OF INVENTION
This invention relates to the selective solution coating of
extruded surfaces and more particularly to a process and apparatus
for selectively coating one or more surfaces of extrudate emerging
from an extruder die by providing a solution coating means
generally adjacent the extruder die.
BACKGROUND
Various types of extruded articles require surface coatings be
applied to a plurality of selected surfaces without coating the
entire surface of the extruded article. For instance, extruded
elastomeric articles such as automotive window and door seals,
fluid hoses, weather stripping and the like are extruded in
specific cross-sectional designs which often require selective
surface coating of separated surfaces. For example, automotive
window seals require special slip- and abrasion-resistant surface
coatings adjacent the window for engaging the glass so it can be
raised or lowered easily without sticking to the window seal
engaging surface. The remaining surfaces are generally maintained
free of such coatings.
U.S. Reissue Pat. No. 30,789, relates to a process for coating an
inflexible sheet substrate with a relatively thick coating of
extruded molten thermoplastic polymer to coat the sheet substrate
with a thermoplastic plastic layer to form boards used in
construction. The sheet substrate advances in a spaced relationship
with the die lip of the applied molten thermoplastic while the
advancing sheet substrate forms the second die lip of the extrusion
coating die. The sheet substrate ordinarily is wood, although other
substrates, e.g., metal or polymeric, can be used. This coating
process is not practiced in conjunction with an extruded substrate
and utilizes a preformed substrate.
U.S. Pat. Nos. 3,841,807, and 3,836,297, relate to rotating coating
application devices in an oscillating relationship with an
advancing sheet substrate for depositing two separate coatings on
the substrate surface to provide a heat-fused, marbleized plastisol
coating on the substrate. This coating application process is not
used in conjunction with an extruded substrate.
U.S. Pat. No. 3,155,540, relates to extrusion coating of fabrics by
progressively feeding fabric and extruding coating material onto
the fabric in a predetermined design and fusing the coating
material to the fabric substrate. Similarly, U.S. Pat. No.
4,623,501, pertains to photographic photosensitive materials where
photographic emulsions are applied to a belt-like substrate (web)
by a coating means having auxiliary coating supply pipes
interconnected to the coating application reservoir to prevent the
coating from being stagnated within the coating supply cavity prior
to applying the coating to the substrate.
U.S. Pat. No. 4,093,414, relates to a single die for co-extruding a
high density polyethylene skin layer in a concentric relationship
over a cellular polyethylene primary layer where the extruded
layers provide cylindrical insulated layers for telephone wires.
The two layers of insulating material are applied successively with
a melt-flow separator disposed between the insulating layers prior
to merging proximate the discharge tip of an extruder for the
telephone wire. Similarly, U.S. Pat. No. 4,889,669, relates to a
process for extruding two different resin compositions in the form
of a laminate through a T-die to produce a foamed thermoplastic
article. A similar coextrusion process for thermoplastic articles
is disclosed in U.S. Pat. No. 4,856,975, wherein flat articles such
as siding are extruded. The coextrusion process is based on a
coextrusion block which enables the extruded capstock material to
straddle the extruded substrate material.
SUMMARY OF THE INVENTION
The coating apparatus of this invention generally comprises a
coating block in conjunction with an extrusion die where protective
or functional solution surface coatings are applied to one or more
surfaces of the extrudate emerging from the extrusion die. The
coating block can be a separate block either attached to the
extruder die block, or separate therefrom, or it can also be an
integral part of the extruder die as an in-die coating block.
Generally, it is a separate block attached to the extruder die. The
coating block contains at least one and preferably a plurality of
coating reservoirs or chambers, each fitted with an applicator
means and adapted to apply surface coatings only onto selected
surfaces of the extrudate emerging from the extrusion die. The
applicator means supplies at least one liquid solution polymer
coating to an in-die coating cavity having surfaces conforming to
the selected surfaces of the extruded substrate to be coated. The
process of this invention comprises extruding a substrate having
designated surface areas to be coated with solution coatings such
as polymer or other liquid coatings and coating the designated
surface areas as the extrudate emerges from the extrusion die and
contacts the coating cavity.
The process and apparatus of this invention can advantageously
apply protective or functional solution coatings such as polymer
coatings to multiple surfaces generally laterally spaced,
vertically displaced, and the like, depending on the
cross-sectional configuration of the extruded substrate. The in-die
coating process advantageously provides essentially 100 percent
transfer efficiency of generally solvent-based coating within the
coating block to the selected extrudate surfaces without
undesirable solvent emissions. Moreover, general surface areas of
the extrudate substrate can be coated without masking.
Post-extrusion coating steps displaced from the extruder such as
brushing or spraying are thus eliminated. Various protective or
functional coatings which can be applied in accordance with the
present invention include solution polymer cosmetic or decorative
coatings, abrasion resistance or low friction slip coatings,
weather-resistant coatings, freeze-resistant coatings and the like.
These and other advantages of the invention will become more
apparent by referring to the drawings and detailed description of
the invention.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of the coating apparatus of this
invention showing a coating block in conjunction with an extrusion
die plate;
FIG. 2 shows a front view of the extrusion die plate shown in FIG.
1;
FIG. 3 is an enlarged front elevation view of the coating block
shown in FIGS. 1 and 2, and also shows the coated extrudate;
FIG. 4 is an enlarged cross-sectional view taken along lines 4--4
in FIG. 1; and
FIG. 5 is a vertical cross-sectional view of the coating block
taken through channel 48 of FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, a coating block 10 is aligned
and secured to an extrusion die plate 12 disposed on the front end
of an extruder 14. The invention further contemplates the use of
one or more coating supply sources which, desirably through
individual pumps for each, are connected to specific supply lines.
For example, as seen in FIG. 1, a coating block 10 is attached to
the extruder die plate 12 and further interconnected to three
coating supply pipes 16, 17, 18, and respective pumps 20, 21, 22,
and coating supply sources 24, 25, and 26. As seen in FIGS. 2 and
3, the supply pipes 16, 17, 18 are attached to the front surface of
the coating block 10 by individual quick-disconnect couplings 28,
29, 30, respectively, to enable simple interconnection with the
coating supply sources. The use of three separate supply lines 16,
17, 18 permits use of three different coatings, if desired, and
also provides individual control of each coating line where applied
pump pressure to each line may be varied if desired to provide
varied flow rates and/or applied pressure to form variable applied
coating thicknesses to three separate extrudate surfaces. A single
coating supply line containing a solution polymer can be used to
supply the coating block with its total solution coating supply
although separate coating supply lines 16, 17, 18 are
preferred.
As seen in FIG. 3, the coating block 10 is secured to the extrusion
die plate 12 by a plurality of bolt means 32. The coating block 10
contains a multi-surface coating cavity 35 having the same general
cross-sectional configuration as the extrusion die 12. The coating
die cavity 35 contains unconnected coating surfaces 38, 40, 42 best
viewed in cross-sectional FIG. 4 which particularly shows the
coating means for supplying coating to the respective coating
surfaces 38, 40, 42. The coating means comprises cylindrical
chambers 16a, 17a, 18a disposed in the solid coating block 10 and
communicating with coating feed lines 16, 17, 18 respectively. The
solution coating such as a polymer coating material is supplied
under moderate positive pressure actuated by the individual pumps
20, 21, 22, which can be independently adjusted to supply the
coating under pressure to the internal cylindrical chambers 16a,
17a, 18a, as desired.
As shown in FIG. 4, each individual chamber 16a, 17a, 18a
communicates with generally downwardly depending narrow channels
46, 48, 50, respectively, which are generally located in the back
of the coating block adjacent the extrusion die 12 and can
communicate therewith, terminating in narrow slit applicator
openings 60, 61, 62. The slit applicator openings 60, 61, 62 are
narrow in depth (i.e., axial height of the coating block), but
particularly broad in breadth to accommodate the coating profile
breadth desired to be applied to the selected surfaces of the
extruded substrate 52. In this regard, internal chamber 18a
communicates with a wide profile channel 50 and a wide applicator
slit 62 adapted to apply measured amounts of liquid coating to die
cavity surface 42 within the coating block 10. Similarly, internal
chamber 17a communicates with a narrow profile channel 48 and a
narrow applicator slit 61 to supply measured amounts of coating to
die cavity surface 40 while internal chamber 16a communicates with
an intermediate channel 46 and an intermediate applicator slit 60
to supply measured amounts of liquid coating to die cavity surface
38. The downwardly depending channels 46, 48, 50 are all generally
relatively narrow in thickness (depth), but vary in breadth to
provide the breadth of coating profile desired. Each internal
chamber 16a, 17a, 18a, in conjunction with the respective coating
application channels 46, 48, 50, individually functions as flow
coating means under minor positive pressure to provide separate
linear coatings to separate surface areas. The desired linear
coating surfaces can be laterally displaced, or vertically
displaced, or both laterally and vertically displaced, as shown in
FIG. 4. They furthermore can be of any desired configuration. The
applied solution coatings can be continuous or intermittent, as
desired, by operatively controlling pumps 20, 21, 22 or other
coating supply control means.
The coated extrudate is best seen in FIG. 3, containing linear
coatings 55, 56, 57 applied to separate surfaces of the extrudate
by liquid coating passing through channels 46, 48, 50,
respectively, and through applicator openings 60, 61, 62 to
directly apply coatings to the selected surfaces of the extruded
substrate 52. The applied solution coatings can be dried or cured
at ambient temperatures or heat-cured at elevated temperatures if
desired. Preferred coatings are solvent-based polymers and, hence,
heat is not required to fuse coatings to extrudate surfaces.
In accordance with this invention, one or more solvent solution
coatings can be transported and applied to one or more separate
selected surfaces on an extruded substrate. Each coating for each
respective selected surface is supplied through a pumping and feed
line system to the coating block 10 which, by coating means,
applies a coating to a preselected surface of the extrudate in
specific metered amounts. Quick-disconnect couplings 28, 29 30 are
provided at the coating block as well as being provided at various
points in the coating supply lines 16, 17, 18, such as at the pumps
20, 21, 22, or the coating supply sources 24, 25, 26, and permit
and facilitate interchange of coating sources with intended coating
surfaces, if desired. In order to prevent running on the substrate
surface, the solution coating viscosity should be from about 100 to
about 500 centipoise, desirably from about 150 to about 500
centipoise, and preferably from about 200 to about 400
centipoise.
The extrudate can be an elastomer, a thermoplastic elastomer, or a
thermoset. Useful thermoplastics include polyvinyl chloride,
acrylonitrile-butadiene-styrene, various polyolefins made from
monomers having from 2 to about 7 carbon atoms with specific
examples including polyethylene, polypropylene, etc., or other
conventional polymers known to the art and to the literature.
Useful thermosets include, for example, polyurethane and various
types of rubber such as styrene-butadiene rubber, EPDM rubber
(ethylene-propylenediene copolymer), natural rubber, butyl rubber,
neoprene, blends of EPDM-SBR and EPDM-neoprene blends, as well as
other rubbers known to the art and to the literature. Examples of
suitable thermoplastic elastomers include blends of polypropylene
and EPDM, e.g., Santoprene.RTM., blends of PVC and EPDM, e.g.,
Sunprene.RTM., as well as other compounds known to the art and to
the literature. The extrudate, be it an elastomer, a thermoplastic
elastomer, or a thermoset, can contain suitable reinforcing fibers
such as glass, boron, graphite, polyester, nylon, and the like, as
well as plastic, or metal reinforcement. The extruded substrate can
also be aluminum. EPDM is a preferred substrate.
The solution coatings which can be applied to the extrudate
surfaces are generally unlimited so long as they can be dissolved
by a suitable solvent known to the art and to the literature,
usually organic, or water-based systems, i.e., where water is a
solvent, or water-borne systems, i.e., where water is utilized with
a co-solvent. An amount of solvent is generally utilized with the
desired coating to conform to the above-noted viscosity range of
from about 100 to about 500 centipoise. Organic solvents generally
include hydrocarbon solvents such as aliphatic hydrocarbons,
aromatic hydrocarbons, chlorinated hydrocarbons, aliphatic
substituted hydrocarbons, etc., as well as combinations thereof.
The useful solution polymer coatings can be cosmetic or decorative
coatings to achieve a desired aesthetic effect, or functional
surface coatings to impart abrasion resistance, low friction, good
weatherability, freeze resistance, and similar functional qualities
to the surface coated. Exemplary cosmetic coatings can include
polymers such as polyurethanes, polyesters, polyethers,
fluorocarbons, silicones, acrylics, vinyls, and the like.
Functional coatings include, for example, various polymers such as
polyurethanes for high abrasion resistance, polyesters for
weatherability, and silicones and Teflon.RTM. polymers for low
friction resistance, and the like. Other coatings include flock
adhesives, for example nylon or polyester fibers which are
electrostatically applied while coating surfaces 55, 56, or 57 are
still viscous. In addition to polymer solution coatings, other
liquid materials having a suitable non-run viscosity can be
utilized such as various lubricants, soaps, paints, and the like,
which are known to the art and to the literature.
The type of extruder which can be utilized is not critical and can
include a single screw, twin screw, a cross-head extruder, or one
or more extruders but only one extrusion die. The extrudate
substrate can include a wide variety of extruded articles such as
automotive seals for windows or doors, fluid transport hoses,
weather stripping, and similar extruded articles which require
specifically selected surface coated areas.
In accordance with the process of the present invention, liquid
solution coatings such as polymers are supplied to a coating block
containing a die cavity 35 having coating surfaces 38, 40, 42
conforming to the selected surfaces on the extruded substrate 52 to
be coated. The extruded substrate emerges from the extrusion die
plate 12 and enters the coating block 10 where the selected surface
on the extruded substrate communicates with the conforming coating
surfaces 38, 40, 42, whereupon liquid coating supplied to internal
chambers 16a, 17a, 18a discharges through narrow channels 46, 48,
50, respectively. The liquid solution polymer coating passes
through applicator openings 60, 61, 62 in the coating die cavity
35, and coating surfaces 38, 40, 42, to directly apply liquid
coating as an applied film to the selected surfaces of the extruded
substrate.
In accordance with another embodiment of the present invention,
coating block 10 need not be attached to extrusion die plate 12,
but can be located downstream a sufficient distance so that, for
example, the extrudate can be cured to a stable profile, and then
reoriented to coat, for example, the area of the part that would
normally ride on the curing belt. In addition, it may be desirable
to coat a cosmetic or functional coating at the extruder and cure
this coating, and downstream apply a flock adhesive and nylon or
polyester flock to a different location on the extrudate. This
process also eliminates flock contamination of the coating. In this
embodiment, the various coatings are applied in the same or similar
manner as set forth hereinabove to selected surfaces of the
extrudate.
Alternatively, the coating block can actually be a part of the
extrusion die and thus contain the same channels 46, 48, 50,
coating surfaces 38, 40, and 42, applicator openings 60, 61, 62,
and the like, therein.
While the above description relates to a preferred embodiment, it
is apparent that the coating block can apply one or more solution
coatings via one or more individual supply lines using one or more
pumps through one or more coating block channels, each of which can
communicate with one or more, but preferably only one, application
openings to coat one or more surfaces. It should thus be obvious
that the present invention includes a great number of permutations
for applying a solution coating to a preselected surface of an
extrudate. Another advantage of the present invention is that
inasmuch as the coating material is directly applied to a selected
extrudate surface, there is no wasted solution coating.
While in accordance with the Patent Statutes, the best mode and
preferred embodiment has been set forth, the scope of the invention
is not limited thereto, but rather by the scope of the attached
claims.
* * * * *